Authorities have said 20-year-old Tyler Peterson went to an all-night pizza party in the northern Wisconsin town of Crandon on Oct. 7 and killed six people, including his ex-girlfriend. Neitzel was wounded by three shots. Police tracked Peterson to a cabin later in the day, but he killed himself as they closed in, officials said.

Neitzel said he did not know why the off-duty Forest County Sheriff's Department deputy and part-time Crandon police officer attacked the group, the newspaper reported Monday.

"I guess nobody will really know why he did it," Neitzel said. "The only person that can really know is him, I guess. He's a cold-blooded murderer. That's all there is to it."

He said Peterson showed up after the small party started at the home of Jordanne Murray and said he and Murray were supposed to hang out that night.

"She said 'Well, plans have changed and now I have different people over and I want you to leave,"' he said.

Neitzel said Peterson did not want to leave and swore at Murray as some of the others yelled at him, "telling him to leave, telling him that he was being a psycho, a stalker boyfriend, because he pretty much was," Neitzel said.

Peterson "was a crazy psycho when he came flying in that door," Neitzel said.

After pushing Murray and striking one of the other women, Peterson ran out the door, then returned with an AR-15 rifle, kicked in the door and opened fire, he said.

Neitzel said he was shot first in one leg.

"I tried to stand up and my leg just, like, snapped ... I was standing there on my one leg and I looked at him. I was screaming at him not to shoot me. I was like 'Tyler, There's no reason you have to shoot. Don't [expletive] shoot me! We've been friends forever."'

When Peterson paused, Neitzel said, he went for the gun but Peterson shot him in the elbow.

"I fell on the ground. I curled up in the corner and I just played dead," said Neitzel, who also was shot in one shoulder.